NCEI added Alaska climate divisions to its nClimDiv dataset on Friday, March 6, 2015, coincident with the release of the February 2015 monthly monitoring report. For more information on this data, please visit the Alaska Climate Divisions FAQ.

Wildfire activity during June was remarkably low, given the above–average activity earlier in the year. The number of fires in June was the fewest in the past decade, while the total acreage burned across the nation during the month ranked eighth out of the last ten years. These low values correspond in part to the well above average precipitation across large parts of the intermountain western U.S. June began with nine large fires in six states (three in Arizona, two in Oregon, and one each in Alaska, California, New Mexico, and Florida). At mid–month, dry conditions in Alaska had resulted in several large fires in the interior of the state. Six additional large fires were active in Arizona (4), New Mexico (1), and Florida (1). The end of June saw very low fire activity, with no active large fires in Alaska or Arizona, and just three in California and one in Texas.

According to statistics from the National Interagency Fire Center (NIFC), between May 29th and June 30th approximately 525,937 acres (212,839 hectares) were burned across the United States. The total acreage burned during June 2009 was 435,409 acres (176,204 hectares) below the 2000–2009 average of 961,346 acres (389,043 hectares), and for that 10–year period was the third lowest June for acreage burned. A total of 6,864 new wildfires were reported, which is 3,785 fewer than the 2000–2009 average of 10,649 fires. This is the fewest fires in June in the past decade. Average fire size in June 2009 was 76.6 acres (31.0 hectares) burned per fire. This value is 13.1 acres (5.3 hectares) per fire below the 2000–2009 average fire size of 89.7 acres (36.3 hectares) per fire. Since 2005, the total acreage burned in June has steadily decreased at a rate of approximately 200,000 acres (81,000 hectares) per year. This decline is mirrored by a similar decline in the number of June fires, which, since 2006 have decreased at a rate of approximately 2,500 fires per year.

For the period January 1st through June 30th, total year–to–date acreage burned was 1,903,247 acres (770,217 hectares), which was just 24,227 acres (9,804 hectares) below the 2000–2009 average of 1,927,474 acres (780,021 hectares), and the fourth greatest amount of acreage burned for the period since 1999. The year–to–date (January – June) number of fires was 48,192, or 6,292 fires above the 2000–2009 average of 41,900 fires. This ranks 2009 as the third highest year–to–date for number of fires over the past decade. Combined, the year–to–date number of fires and acreage burned yields an average of 39.5 acres (16.0 hectares) per fire.

According to the U.S. Drought Monitor, areas of southern Texas experienced severe to exceptional drought conditions through the month of June, exacerbating potential fire danger in that region. Drought conditions also worsened across the Hawaiian Islands and remained in moderate to severe drought status across the majority of California as well as the upper Midwest during the month.

A wet June in the eastern U.S. served to lower the observed fire danger there through the month. The U.S. Forest Service (USFS) – Wildland Fire Assessment System indicated low to moderate fire danger existed across much of the United States, including Alaska in June. At the start of June, high to very high danger existed in southern California, Nevada, and Arizona, as well as much of New Mexico, the lower Mississippi drainage, and parts of Maine, southern Minnesota, and the Pacific Northwest. By June 14th, high to extreme fire danger was concentrated in Arizona, southern Nevada, Utah and New Mexico, and western Texas. Small areas of high fire danger also were present in Minnesota and the lower Mississippi River drainage. High to very high danger in the southwestern U.S. migrated from the Arizona – West Texas corridor to a region bounded by the Pacific coast of southern California, western New Mexico, and northern Utah and Nevada. Elsewhere, high to very high danger developed in parts of Wyoming, Montana, and Washington, and expanded to cover much of Mississippi at the end of June.

The very low 10–hour dead fuel moisture levels across much of the western United States at the end of May was somewhat alleviated by the middle of June. By mid–month, critically low 10–hr dead fuel moisture levels were present primarily in western Texas and southeastern New Mexico, and from the Arizona–Mexico border northward to central Utah. Dry conditions across New England were ameliorated by ample precipitation early in the month. Unfortunately, the second half of June saw widespread drying of 10–hr fuels across nearly all of the western United States, as well as much of the Southeast north of Florida. Critically dry tinder also was present throughout much of eastern Alaska at the beginning of June. By mid-June, the dry conditions had shifted to the northern half of the state, and by the end of the month, moderate to critically dry conditions covered most of Alaska.

Low 100–hour and 1000–hour fuel moisture levels were present across much of the west–central United States at the beginning of June, with critically dry 100–hr moisture levels in the Southwest and Northwest. Low 100–hr moisture levels also existed throughout the middle of the country and in parts of the mid–Atlantic region. Mid–June brought improved 100–hr fuel moisture levels to a swath of the country that meandered from Oregon to South Dakota, southeastward to northern Mississippi, and finally northeastward to Maine. Critically low moisture levels expanded in western Texas and Arizona. At the end of the month, moist 100–hr fuels existed only in Florida, the Northeast, and the Great Lakes. Critically low levels covered much of the western U.S. at the end of June. Low to moderate larger fuel moisture levels covered Alaska in June.

The Keetch–Byram Drought Index (KBDI), a widely used drought index for fire risk, showed a marked increase in fire–related drought conditions across much of the western Gulf Coast during June. Conditions also deteriorated in southwestern Arizona and much of Nevada throughout the month. The KBDI showed relatively moderate conditions across Alaska for June.

Citing This Report

NOAA National Centers for Environmental Information, State of the Climate: Wildfires for June 2009, published online July 2009, retrieved on December 9, 2016 from http://www.ncdc.noaa.gov/sotc/fire/200906.